// Table layout support for generating anonymous table elements
// Based on CSS 2.1 Section 17.2.1: Anonymous table objects

use alloc::vec::Vec;

use azul_css::props::layout::LayoutDisplay;

use crate::{
    dom::{NodeData, NodeType},
    id::NodeId,
    styled_dom::StyledDom,
};

/// Error type for table anonymous element generation
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum TableAnonymousError {
    /// Invalid node ID provided
    InvalidNodeId,
    /// No display property found for node
    NoDisplayProperty,
}

/// Generates anonymous table elements according to CSS table layout rules.
///
/// This function works on StyledDom (not Dom) because it needs access to computed
/// CSS display property values to determine which elements need wrapping.
///
/// This function ensures that:
/// - Table elements have proper table-row and table-cell children
/// - Non-table children of tables are wrapped in anonymous table-row and table-cell boxes
/// - The resulting DOM tree is suitable for table layout algorithms
/// - All generated anonymous nodes are marked with is_anonymous=true
///
/// Must be called after CSS cascade but before layout calculation.
///
/// Implementation follows CSS 2.2 Section 17.2.1:
/// - Stage 1: Remove irrelevant whitespace
/// - Stage 2: Generate missing child wrappers
/// - Stage 3: Generate missing parents
pub fn generate_anonymous_table_elements(
    styled_dom: &mut StyledDom,
) -> Result<(), TableAnonymousError> {
    // TODO: Implement the full 3-stage algorithm
    // This is a complex task that requires:
    // 1. Traversing the entire tree
    // 2. Identifying nodes with table display values
    // 3. Checking if their children have correct display values
    // 4. Inserting anonymous wrapper nodes where needed
    // 5. Marking all generated nodes with is_anonymous=true
    //
    // For now, this is a placeholder that returns Ok(())
    // The actual implementation will need to:
    // - Access styled_dom.node_hierarchy for tree structure
    // - Access styled_dom.node_data for node information
    // - Access styled_dom.css_property_cache for display properties
    // - Insert new nodes into both hierarchy and data containers
    // - Update parent-child-sibling relationships
    //
    // This is left for future implementation as it requires careful
    // manipulation of the arena-based data structures.

    Ok(())
}

/// Helper function to check if a display value represents a proper table child
fn is_proper_table_child(display: &LayoutDisplay) -> bool {
    matches!(
        display,
        LayoutDisplay::TableRowGroup
            | LayoutDisplay::TableHeaderGroup
            | LayoutDisplay::TableFooterGroup
            | LayoutDisplay::TableRow
            | LayoutDisplay::TableCaption
            | LayoutDisplay::TableColumn
            | LayoutDisplay::TableColumnGroup
    )
}

/// Helper function to check if a display value represents a table row
fn is_table_row(display: &LayoutDisplay) -> bool {
    matches!(display, LayoutDisplay::TableRow)
}

/// Helper function to check if a display value represents a table cell
fn is_table_cell(display: &LayoutDisplay) -> bool {
    matches!(display, LayoutDisplay::TableCell)
}

/// Helper function to check if a display value represents a table or inline-table
fn is_table_element(display: &LayoutDisplay) -> bool {
    matches!(display, LayoutDisplay::Table | LayoutDisplay::InlineTable)
}

/// Helper function to get the computed display property for a node
fn get_node_display(styled_dom: &StyledDom, node_id: NodeId) -> Option<LayoutDisplay> {
    // Get display property from CSS property cache
    let cache = styled_dom.get_css_property_cache();
    let node_data = &styled_dom.node_data.as_ref()[node_id.index()];
    let node_state = &styled_dom.styled_nodes.as_container()[node_id].state;

    cache
        .get_display(node_data, &node_id, node_state)
        .and_then(|value| value.get_property().cloned())
}

#[cfg(test)]
mod tests {
    use super::*;

    // TODO: Add tests for StyledDom-based anonymous table element generation
    // These tests will need to:
    // 1. Create a StyledDom with incomplete table structure
    // 2. Call generate_anonymous_table_elements()
    // 3. Verify anonymous nodes are inserted correctly
    // 4. Verify is_anonymous flag is set on generated nodes
    // 5. Verify original structure is preserved
}
